Sakuya Watanuki

 Sakuya Watanuki (綿貫桜哉, Watanuki Sakuya) is a member of Tsubaki's subclass and Mahiru Shirota's best friend.

Appearance
While his actual age is unknown, Sakuya is physically 15 years old. He has green hair and often wears green clothing. His eyes are red as a result of becoming a vampire. He is often seen wearing his pink headphones.

Personality
By his classmates, Sakuya is known as the class clown, as he is always making jokes and telling rumors of nearby vampires in an effort to scare his friends. The only friend who knows his true identity, however, is Mahiru.

Sakuya is shown feeling a conflicting loyalty between Mahiru and Tsubaki. He will not betray Tsubaki because he knows that Tsubaki will not betray him. Sakuya is shown to be quite upset upon finding out Mahiru had been lying to him and pretended to hate Mahiru in an attempt to get Mahiru to kill him.

History
In his past, Sakuya's older sister was driven to suicide by their parents, who said it was an accident in order to receive money from life insurance. Sakuya knew the truth but was forced to lie about the situation. Before her death, Sakuya's sister made their parents promise not to hurt Sakuya. While in his adolescence, Sakuya suffered the same fate as his sister. After this occurred, Tsubaki made Sakuya a vampire and one of his subclass.

Relationships
Quotes
 * "I was born in a town of liars, as a child of liars. A year ago I sneaked into a middle school to kill time, but in truth I probably wished for something else. [...] Just like that, because of that hand and that voice, I thought... "Man, I'd love to be friends with this guy." Mahiru... thank you for finding me... thank you for reaching out to me...!" (about Mahiru Shirota)

Trivia
Sakuya Watanuki
 * Sakuya's favourite dish is Okonomiyaki ( お好み焼き )
 * He dislikes lies
 * His hobbies are browsing through music shops
 * His best subject is Math
 * His worst subject is Ethics and Japanese (especially modern Japanese)
 * His fave color is firefly green
 * In the Drama CD "The vampire-only summer vacation" Sakuya admits that he'd like to be called "Sakkun"
 * In the April Fool's Day "SERVAMP School" announcement, it is stated that the way he would pursue Mahiru by insisting on walking him home everyday while proclaiming his undying love to him.
 * The author said that they like Sakuya because he is  'yandere'.
 * In the first popularity poll he came third with 2000 votes.